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Organisationseinheit der BAM
Eingeladener Vortrag
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This key comparison was performed to demonstrate the capability of NMIs to analyse the purity of methane for use as a source gas in the preparation of standard gas mixtures. This capability is an essential requirement for the preparation of accurate standards of natural gas and some other fuels.
Since it is difficult to carry out a comparison with individual samples of pure gas, the sample for this comparison was a synthetic mixture of high purity methane with selected added impurities of nitrogen, argon, carbon dioxide and ethane. These mixtures were prepared by a gas company as a batch of 10 cylinders and their homogeneity and stability were evaluated by NMIJ.
The KCRVs for the four different analytes in this key comparison are based on a consensus of values reported by participants. The uncertainties in the degrees of equivalence were calculated by combining the reported uncertainties with the homogeneity of the samples and the uncertainty of the KCRV. The results submitted are generally consistent with the KCRV within the estimated uncertainties.
Finally, this comparison demonstrates that the analysis of nitrogen, argon, carbon dioxide and ethane in methane at amount fractions of 1 µmol/mol to 5 µmol/mol is generally possible with an uncertainty of 5% to 10%.
Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
DatesIssue 1A (Technical Supplement 2012)
It is important to evaluate the effect of thermal ageing on the sealing performance of metal gaskets under high temperature for long-term usage. Therefore, in order to gain representative data for this kind of metal-sealed lid System, BAM is currently performing laboratory tests of different gasket types with aluminum and silver jackets at three different temperatures under static conditions up to four years so far, using test flanges for gaskets with full scale cross section diameter but much smaller outer diameter. On the other hand, in order to investigate the applicability of the numerical methodology to evaluate the long-term behavior of the metal gaskets, such as a correlation between seal pressure force and holding time, CRIEPI is developing a modeling method including material tests (tensile and creep tests) at high temperature. In this paper, the applicability of the finite element method (ABAQUS) to predict the recovery displacement and residual seal pressure force of the gasket complex was verified by comparing the calculated values with BAM’s laboratory test results under the joint research agreement between BAM and CRIEPI.
2,2-Dibutyl-2-stanna-1,3-dioxepane (DSDOP) was polycondensed with bis(4-chlorothiophenyl) suberat under various reaction conditions, but only moderate molecular weights (Mn 10000) were obtained. The MALDI-TOF mass spectrosmetry revealed the formation of cyclic oligo- and polyesters in addition to linear species having OH, CO2H, and unreacted 4-chlorothiophenyl ester endgroups.
Furthermore, -Caprolactone (-CL) was polymerized with DSDOP as the initiator at monomer/initiator (M/I) ratios of 20 and 50. The resulting tin-containing macrocyclic polylactones were reacted with sebacic acid bis(4-thiocresyl)ester at three different temperatures and with different reaction times. Analogous polycondensations were conducted with suberic acid bis(4-chlorothiophenyl) ester. The presence of thioarylester endgroups in the isolated polyesters was checked by 1H NMR spectroscopy. The highest conversions were found at long reaction times (24 or 72 hours), or after the addition of pyridine and N,N-dimethylaminopyridine as catalysts. Despite high conversions, the number average molecular weights (Mn's) did not exceed values around 20000. Even in the samples having the highest molecular weights, unreacted 4-chlorothiophenylester endgroups were detected by GPC measurements evaluated with a UV-detector. It is concluded that both factors, cyclization and incomplete conversion, contribute to the limitation of the chain growth.
The fracture toughness in the fiber-matrix composite by means of the single fiber pull-out test can be achievable, if it is possible to measure the compliance of partial debonded fiber, which necessitates a stable crack propagation and the determination of the corresponding crack length. A combination of high stiff test equipment and a simultaneous monitoring of the photo-elastic pattern of the embedded fibers with the help of polarization microscope enables to measure crack length and determination of Gc [Hampe, A and Marotzke, C. (1997). The Energy Release Rate of the Fiber/Polymer Matrix Interface: Measurement and Theoretical Analysis, J. Reinf. Plast. and Compo., 16: 341-352.]. This method is well-known for glass fiber-amorphous polymer composite. In this investigation, we tried to implement the same technique to C-fiber with amorphous and semi-crystalline polymer composites. The energy release rate (ERR) of the fiber-matrix interface was evaluated for the carbon fiber-reinforced in polycarbonate (PC) by interfacial crack propagation arising in the single fiber pullout test. Further, the crack propagation at the fiber-matrix interface with different matrix morphology was discussed with the use of photo-elastic pattern observed with the aid of polarization microscope.
Die in zunehmenden Maße Mitte der 80er Jahre einsetzende Substitution von metallischen Materialien z. B. durch hochleistungsfähige polymere Werkstoffe und Verbundwerkstoffe wurde u. a. von der DGM zum Anlass genommen, ihre zukünftigen Aufgaben neu zu definieren und gleichzeitig mit der Gründung des Fachausschusses "Gefüge und Eigenschaften von Polymerwerkstoffen" dieser neuen Entwicklung in der Materialkunde auf dem Gebiet der Kunststoffe und ihrer Anwendungen Rechnung zu tragen.
Haben Sie sich schon einmal überlegt, was unter Ihren Füßen
geschieht, wenn Sie über eine Wiese gehen? Könnten
Sie beschreiben, wie es im Boden aussieht? Wie ist die
Struktur des Bodens, wie breiten sich darin die Wurzeln
der Pflanzen aus und wie ist die Wasserverteilung im Porenraum,
welche die Umsatzprozesse im Boden bestimmt?
Diese Fragen können Sie beantworten, wenn sie die Möglichkeit
nutzen, den Boden mittels Computertomographie
visuell darzustellen und quantitativ zu analysieren. Dazu
müssen Sie aber zunächst nicht nur eine Probe, sondern statistisch
relevant viele Proben aus dem Boden entnehmen.
Eine Maschine zur zerstörungsfreien Bodenprobenahme
ist notwendig. Wir beschreiben hier den Aufbau und den
Einsatz eines solchen Gerätes und zeigen erste dadurch gewonnene
Makro- & Mikro-Computertomographiebilder.
Atmospheric-plasma fluorination was used to introduce fluorine functionalities onto the surface of carbon fibers without affecting their bulk properties. The interfacial adhesion between atmospheric-plasma-fluorinated carbon fibers and poly(vinylidene fluoride) (PVDF) was studied by means of direct wetting measurements and single fiber pullout tests. Measured contact angles of PVDF melt droplets on modified carbon fibers show that short exposure times of carbon fibers to atmospheric-plasma fluorination (corresponding to a degree of surface fluorination of F/C = 0.01 (1.1%)) leads to improved wettability of the fibers by PVDF melts. The apparent interfacial shear strength as a measure of practical adhesion, determined by the single-fiber pullout test, increases by 65% under optimal treatment conditions. The improved practical adhesion is not due to the formation of transcrystalline regions around the fibers or a change of the bulk matrix crystallinity or to an increased surface roughness; it seems to be due to the compatibilization of the interface caused of the atmospheric-plasma fluorination of the carbon fibers.